U.S. Pat. Nos. 5,297,617 and 5,445,215, both entitled "FAN WITH HEAT SINK", and owned by the same entity as this patent application, teach that the area surrounding the fan blade tips in an axial flow fan has high velocity, very turbulent air, and that the periphery of an axial flow fan is an excellent heat sink, particularly if the inside of the fan duct and/or the fan blade are modified as taught therein to enhance the heat sinking. These are modified axial flow fans, and the air flow through them may be partly or completely redirected to fins or other features in the periphery of the fan duct, to remove heat therefrom. These patents are incorporated herein by reference.
It is well known that a plurality of closely spaced fins makes an excellent heat sink. However, the pressure drop through such a heat sink is substantial, requiring a large fan, and there are problems getting the heat to the plurality of fins. Circulating fluid through tubes therein is one way, and radiators such as those found in automobiles are an example.
Heat sinks made with a plurality of closely spaced fins are sometimes made by bonding heat sink fins into a grooved plate. A separate fan may blow air over the fins.